It is often desirable to obtain a measure of the temperature of a fluid (e.g. a liquid or gas) inside of an enclosed tank, such as a water heater tank. While water heaters are described below as one example application, it should be recognized that there are many other applications where it may be desirable to obtain a measure of the temperature of a fluid inside of an enclosed tank or pipe. For example, in some industrial applications, it may be desirable to obtain a measure of the temperature of a fluid passing through a supply pipe that is supplying a constituent to an industrial process. In another example, in a food processing application, it may be desirable to obtain a measure of the temperature of a fluid that is in a distilling tower or a fermenting vat. These are just some examples.
Water heaters are used in homes, businesses and just about any establishment having the need for heated water. A conventional water heater typically has at least one heating element or “heater,” such as a gas-fired and/or electric burner. Each water heater also typically has at least one thermostat or controller for controlling the heater. The controller typically receives signals related to the temperature of the water within the water heater tank, often from a temperature sensor that is thermally engaged with the water in the water heater tank.
In some instances, a water heater may operate in accordance with a first temperature set point and a second temperature set point. The difference between the first and second temperature set point may be referred to as the temperature differential of the water heater. When temperature signals from the temperature sensor indicate that the water temperature is below the first set point, for example when the water temperature is below about 120° F., the controller may turn on the heater and the water within the water heater tank begins to heat. After some time, the water temperature within the water heater tank will increase to the second set point, which, for example may be about 140° F. At this point, the controller may cause the heater to reduce its heat output or, alternatively, causes the heater to turn off. This heat cycle begins again when the water temperature within the water heater tank cools down below the first set point.
For a gas fired water heater, a temperature sensor, a gas valve and a controller are often mounted relative to the water heater tank. The controller typically receives a temperature signal from the temperature sensor. In some cases, the temperature sensor may protrude into and may be thermally coupled to the water in the water heater tank. The controller typically is programmed to control the gas valve such that the temperature of the water in the water heater tank remains between the first and second temperature set points, as described above. For an electric water heater, a temperature sensor, a power delivery unit and a controller may be mounted to the water heater tank. In this case, the controller may control the power delivery unit such that the temperature of the water in the water heater tank is kept between the first and second temperature set points as described above.
In some water heater applications, the temperature sensor may be an immersion-type temperature sensor that, when installed, is immersed in the water in the water tank to maximize conductive and convective heat transfer with the water in the water heater tank. Such placement of the temperature sensor may allow for direct contact with the water in the water heater tank, and consequently a fairly accurate measure of water temperature. However, immersion-type temperature sensors typically require a through-hole through the wall of the water tank to accept the temperature sensor and a waterproof seal between the temperature sensor and the water heater tank. Also, if the sensor fails and needs to be replaced, the water must typically be drained from the water heater tank.
In some applications, the temperature sensor may be a non-immersion-type temperature sensor that is not immersed in the water of the water heater tank, but rather senses the water temperature from outside of the water heater tank. In some cases, a non-immersion-type temperature sensor may be placed adjacent to an outer wall of the water heater tank, and no through-hole through the wall of the water heater tank is required. Because there is no through-hole, non-immersion type temperature sensors can often be removed and replaced without draining the water from the water heater tank. What would be desirable is a device and method for mounting a non-immersion type temperature sensor to a tank, such as a water heater tank, that is designed for an immersion-type temperature sensor. This may allow, for example, a contractor to carry just non-immersion type temperature sensors yet still be able to service water heater design for non-immersion type temperature sensors and water heaters designed for immersion type temperature sensors.